The invention relates to air bags that are used to protect drivers in the event of a collision between motor vehicles.
As shown in FIG. 8, an air bag B is mounted on a hub body of a steering wheel S of a motor vehicle, and this air bag B is inflated by a pressurized gas that will be charged thereinto in the event of a collision of the motor vehicle so that a driver D can be protected.
A conventional method of sewing such an air bag comprises the steps of: either overlapping a pair of circular fabrics one upon the other; sewing the overlapping marginal portions in two lines of stitching; and reversing the right and wrong sides so that the two lines of stitching at the marginal end portions are hidden in the inside of the air bag; or regularly sewing the marginal portions of the pair of overlapping circular fabrics; reversing the right and wrong sides; and sewing the marginal portions of the reversed sides so that the marginal end portions can be similarly hidden in the inside of the air bag.
Such reversing serves to make the air bag look nice, but at the same time, it not only complicates the sewing, but also makes it difficult to fold the air bag so compact as to allow it to be accommodated within a limited space provided at the center of the steering wheel, because the edge portion of the reversed air bag becomes bulky.
The invention has been made in view of the above circumstances. Accordingly, an object of the invention is to provide an air bag whose volume as folded is so compact as to allow it to be accommodated in place without involving the reversing operation or losing its aesthetic appearance.